US2003/0204207 A1 discloses a catheter apparatus comprising a cardiac pacer receiving energy from a battery or a capacitor located at the distal end of a catheter. The transmission of energy from the battery or the capacitor to the cardiac pacer is controlled by an optical control line. The control by an optical control line needs an optical pathway and a conversion device for converting optical signals into electrical signals. These optical and opto-electronical components require a lot of space, wherein the space within the catheter and within a heart is limited. The catheter apparatus is therefore quite large, difficult to manufacture and difficult to handle.